The Snow Camp-Saxapahaw study area, in the Carolina slate belt in the Southeastern United States, is notable for large zones of high-sulfidation alteration in arc-related metavolcanic rocks. The area has potential for additional significant pyrophyllite and related aluminosilicate refractory mineral deposits and may have potential for small- to medium-size gold deposits also associated with the high-sulfidation hydrothermal systems. The Carolina slate belt is an elongate zone of mostly low-grade metamorphic rocks of Neoproterozoic to early Paleozoic age that extends from northeastern Georgia to southern Virginia. It is dominated by volcanic rocks but locally consists of fine-grained epiclastic sedimentary rocks. Plutons and subvolcanic bodies have intruded the rocks of the Carolina slate belt in many places and have been important in controlling the metamorphism and in localizing hydrothermal alteration. The Snow Camp-Saxapahaw area is mostly underlain by volcanic and volcaniclastic rocks and lesser amounts of intrusive shallow plutons. The volcanic rocks range in composition from basalt to rhyolite; however andesites, dacites, and rhyodacites are the most abundant. The intrusive bodies are largely granite and quartz monzonite; gabbroic bodies also are common. It was possible to establish the relative ages of only part of these rocks. Two northeast-trending fault zones and fractures divide the map area into three structural blocks; the central block was tilted down to the southwest to form a grabenlike structure. Most of the hydrothermally altered rocks and all of the intensely altered zones are confined to the downdropped block, which we think may have been calderalike in origin. A major volcanic unit, the Reedy Branch Tuff, is limited to the southwestern part of the graben and may be the youngest volcanic rock in the area. Layered rocks record one or more strong folding events, but the diversity of rock types, lack of recognizable stratigraphic markers, and uneven distribution of outcrops prevented comprehensive structural studies. Except for a few late plutons and dikes, all of the rocks of the area have been metamorphosed in middle to upper greenschist facies, and contact aureoles were recognized around some of the plutons. Several relatively small bodies of granitic rock contain plagioclase grains in which primary oscillatory zoning was unaffected by metamorphism. These were interpreted to be post-metamorphic. We think that there were three separate stages of hydrothermal alteration in the complex volcanic terrane in the area. The oldest, an area of at least 8.5 square miles (22 square kilometers), was subjected to an intense hydrothermal alteration, ranging from peripheral zones of quartz-sericite-paragonite through a patchy marginal zone of pyrophyllite, andalusite, and other high-alumina minerals, to almost totally silicified core zones. The second event resulted in large areas of weak to moderate sericitic and propylitic alteration recognizable only in the Reedy Branch Tuff. The last event was related to post-metamorphic plutons. All of the pyrophyllite-andalusite deposits and perhaps most of the gold and silver mineralization can be related to the first period of hydrothermal alteration. The subsequent metamorphism did not produce significant changes in mineral species in the zones of most intense hydrothermal alteration. Gold- and silver-bearing sulfide minerals in fracture zones along the southeastern margin of the graben may also have been deposited during this earliest alteration stage. No metallic mineralization appears to have occurred during the second event. A group of molybdenum-bearing greisenlike bodies formed during the emplacement of the youngest plutons during the post-metamorphic event. One gold-bearing sulfide zone occurs in the exocontact of one such porphyritic stock.
","language":"English","publisher":"U.S. Geological Survey","doi":"10.3133/ofr20061259","usgsCitation":"Schmidt, R.G., Gumiel, P., and Payas, A., 2006, Geology and mineral deposits of the Snow Camp-Saxapahaw area, central North Carolina: U.S. Geological Survey Open-File Report 2006-1259, HTML Document, https://doi.org/10.3133/ofr20061259.","productDescription":"HTML Document","onlineOnly":"Y","costCenters":[],"links":[{"id":192600,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":9212,"rank":100,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.usgs.gov/of/2006/1259/","linkFileType":{"id":5,"text":"html"}},{"id":398767,"rank":3,"type":{"id":36,"text":"NGMDB Index Page"},"url":"https://ngmdb.usgs.gov/Prodesc/proddesc_80583.htm"}],"scale":"24000","country":"United States","state":"North Carolina","otherGeospatial":"Snow Camp-Saxapahaw area","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -79.4647,\n 35.8069\n ],\n [\n -79.28,\n 35.8069\n ],\n [\n -79.28,\n 35.9486\n ],\n [\n -79.4647,\n 35.9486\n ],\n [\n -79.4647,\n 35.8069\n ]\n ]\n ]\n }\n }\n ]\n}","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4adce4b07f02db68646e","contributors":{"authors":[{"text":"Schmidt, Robert G.","contributorId":19243,"corporation":false,"usgs":true,"family":"Schmidt","given":"Robert","email":"","middleInitial":"G.","affiliations":[],"preferred":false,"id":290314,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Gumiel, Pablo","contributorId":78803,"corporation":false,"usgs":true,"family":"Gumiel","given":"Pablo","email":"","affiliations":[],"preferred":false,"id":290315,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Payas, Alba","contributorId":8553,"corporation":false,"usgs":true,"family":"Payas","given":"Alba","email":"","affiliations":[],"preferred":false,"id":290313,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":79585,"text":"ofr20061151 - 2006 - Environmental Setting of the Morgan Creek Basin, Maryland, 2002-04","interactions":[],"lastModifiedDate":"2012-02-02T00:14:12","indexId":"ofr20061151","displayToPublicDate":"2007-01-20T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"2006-1151","title":"Environmental Setting of the Morgan Creek Basin, Maryland, 2002-04","docAbstract":"The Morgan Creek Basin is a 31-square-kilometer watershed in Kent County, Maryland on the Delmarva Peninsula. The Delmarva Peninsula covers about 15,500 square kilometers and includes most of the State of Delaware and parts of Maryland and Virginia east of the Chesapeake Bay. The Morgan Creek Basin is one of five sites selected for the study of sources, transport, and fate by the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) Program's: Agricultural Chemicals: Sources, Transport and Fate study team (Agricultural Chemicals Team, ACT). A key component of the study is identifying the natural factors and human influences affecting water quality in the Morgan Creek Basin. \r\n The Morgan Creek Basin is in the Coastal Plain Physiographic Province, which is a nearly level seaward-sloping lowland with areas of moderate topographic relief. The study area lies within a well-drained upland region with permeable and porous soils and aquifer sediments. The soils are well suited to most field crops.\r\n Agriculture is the principal land use in the Morgan Creek Basin, as well as throughout the entire Delmarva Peninsula. Most agricultural land is used for row crops such as corn, soybeans, and small grains, and slightly less land is used for pasture and hay production involving alfalfa, clover, and various perennial grasses. There are several animal operations in the study area. Farm management practices include fertilizer and herbicide applications, different tillage practices, addition of lime, forested riparian buffers, grassed waterways, and sediment retention ponds. Irrigation in the study area is minimal.\r\n The climate of the Morgan Creek Basin is humid and subtropical, with an average annual precipitation of 1.12 meters. Overall annual precipitation is evenly distributed throughout the year, from 76 to 101 millimeters per month; however, the spring and summer (March - September) tend to be slightly wetter than the autumn and winter (October - February). Anomalously high precipitation can occur in summer/early autumn due to occasional hurricanes and tropical storms. Thunderstorms can also produce relatively high localized precipitation over the Morgan Creek Basin during the summer months.\r\n Mean daily streamflows for Morgan Creek are highly variable, and somewhat flashy due to the relatively small area of the basin. The long-term median base flow for Morgan Creek is 59 percent of total flow, indicating that total streamflow is most often dominated by a sustained ground-water contribution. Surface runoff accounts for the other 41 percent of the water in total streamflow and dominates during and just after precipitation events. \r\n The surficial aquifer in the study area consists of permeable quartz-rich sand and gravel and is underlain by less permeable marine sand, silt, and clay. The depth to water table ranges from less than 0.4 meters below land surface in the floodplain to 12 meters below land surface in upland areas. Ground water generally flows from uplands toward the Morgan Creek floodplain at a variety of depths and time scales. Because the soils and sediments are permeable and porous, some fraction of chemicals applied to the land surface tend to move downward to the water table where they are transported to discharge areas near Morgan Creek.","language":"ENGLISH","doi":"10.3133/ofr20061151","usgsCitation":"Hancock, T.C., and Brayton, M.J., 2006, Environmental Setting of the Morgan Creek Basin, Maryland, 2002-04: U.S. Geological Survey Open-File Report 2006-1151, vi, 28 p., https://doi.org/10.3133/ofr20061151.","productDescription":"vi, 28 p.","numberOfPages":"34","onlineOnly":"Y","costCenters":[],"links":[{"id":190761,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/usgs_thumb.jpg"},{"id":9204,"rank":100,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.usgs.gov/of/2006/1151/","linkFileType":{"id":5,"text":"html"}}],"noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"4f4e4a14e4b07f02db60257e","contributors":{"authors":[{"text":"Hancock, Tracy Connell","contributorId":62295,"corporation":false,"usgs":true,"family":"Hancock","given":"Tracy","email":"","middleInitial":"Connell","affiliations":[],"preferred":false,"id":290296,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Brayton, Michael J. mbrayton@usgs.gov","contributorId":2993,"corporation":false,"usgs":true,"family":"Brayton","given":"Michael","email":"mbrayton@usgs.gov","middleInitial":"J.","affiliations":[{"id":374,"text":"Maryland Water Science Center","active":true,"usgs":true}],"preferred":true,"id":290295,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ,{"id":79586,"text":"ofr20061271 - 2006 - Descriptions and preliminary report on sediment cores from the southwest coastal area, Part II: Collected July 2005, Everglades National Park, Florida","interactions":[],"lastModifiedDate":"2025-04-15T15:30:46.408855","indexId":"ofr20061271","displayToPublicDate":"2007-01-20T00:00:00","publicationYear":"2006","noYear":false,"publicationType":{"id":18,"text":"Report"},"publicationSubtype":{"id":5,"text":"USGS Numbered Series"},"seriesTitle":{"id":330,"text":"Open-File Report","code":"OFR","onlineIssn":"2331-1258","printIssn":"0196-1497","active":true,"publicationSubtype":{"id":5}},"seriesNumber":"2006-1271","displayTitle":"Descriptions and Preliminary Report on Sediment Cores from the Southwest Coastal Area, Part II: Collected July 2005, Everglades National Park, Florida","title":"Descriptions and preliminary report on sediment cores from the southwest coastal area, Part II: Collected July 2005, Everglades National Park, Florida","docAbstract":"Twelve cores were collected from six sites in the southwest coastal area of Everglades National Park, Florida, in July 2005. These six sites create transects up three river systems that are part of the complex network of channels and bays that form the mangrove and coastal glades – Lostmans River system, Harney River system, and Shark River system. The three transects are linked to two cores collected in 2004 from Big Lostmans Bay and Tarpon Bay. A preliminary model of changes in flow through the southwest coastal zone is proposed based on an examination of the sediments and an initial assessment of key indicator species of mollusks within the cores. Throughout the time period recorded by deposition of these cores, flow to the southwest coastal area has been predominantly through the Shark River channels, diminishing to the north toward the Lostmans River system. The Lostmans system was less influenced by freshwater flow and more emergent than the two systems to the south. Freshwater flow has periodically reached the mouths of the Harney and Shark River systems, but these areas have persistently been zones of mixed estuarine environments, typical of transition zones. Evidence for a substantial change in the flow regime is found in the mid-system cores from the Harney and Shark Rivers. The lower portions of both cores were deposited in freshwater environments, with no indication of estuarine influence; however, a shift towards more estuarine conditions occurs in the upper portions of the cores and a loss of the larger freshwater fauna. These results are preliminary. The next step will be to develop age models and to conduct quantitative analyses of the fauna, flora, and sediment geochemistry at these sites. Results of the quantitative analyses will provide information on the natural and anthropogenic changes that have occurred in the southwest coastal system that will allow resource managers to set targets for restoration.
","language":"English","publisher":"U.S Geological Survey","publisherLocation":"Reston, VA","doi":"10.3133/ofr20061271","usgsCitation":"Descriptions and Preliminary Report on Sediment Cores from the Southwest Coastal Area, Part II: Collected July 2005, Everglades National Park, Florida; 2006; OFR; 2006-1271; Wingard, G. Lynn; Budet, Carlos A.; Ortiz, Ruth E.; Hudley, Joel; Murray, James B.","productDescription":"33 p.","numberOfPages":"33","costCenters":[],"links":[{"id":362547,"rank":3,"type":{"id":22,"text":"Related Work"},"url":"https://pubs.er.usgs.gov/preview/ofr20051360","text":"Open-File Report 2005-1360","linkHelpText":"- Descriptions and Preliminary Report on Sediment Cores from the Southwest Coastal Area, Everglades National Park, Florida"},{"id":362546,"rank":2,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/of/2006/1271/ofr20061271.pdf","text":"Report","size":"67.5","linkFileType":{"id":1,"text":"pdf"},"description":"OFR 2006-1271"},{"id":191455,"rank":1,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/of/2006/1271/coverthb.jpg"}],"country":"United States","state":"Florida","otherGeospatial":"Everglades National Park","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"coordinates\": [\n [\n [\n -81.31089678655033,\n 25.805615345913836\n ],\n [\n -81.31089678655033,\n 25.120280550494044\n ],\n [\n -80.43083859375446,\n 25.120280550494044\n ],\n [\n -80.43083859375446,\n 25.805615345913836\n ],\n [\n -81.31089678655033,\n 25.805615345913836\n ]\n ]\n ],\n \"type\": \"Polygon\"\n }\n }\n ]\n}","contact":"St. Petersburg Coastal and Marine Science Center
U.S. Geological Survey
600 4th Street South
St. Petersburg, FL 33701